Filament support for radio tubes and the like



Nov. 23, 1937. H. J. MCCARTHY 2,100,306

FILAMENT SUPPORT FOR RADIO TUBES AND THE LIKE Filed Sept. 28, 1936 INVENTOR ATTORNEY Patented Nov. 23, 1937 UNITED STATES PATENT OFFICE FILAMENT SUPPORT FOR RADIO TUBES AND THE LIKE Application September 28, 1936, Serial No. 102,872

14 Claims.

This invention relates to supporting devices andmore particularly to resilient supports for filaments such for example as are employed in radio tubes, electric lamps and the like.

An object of the invention is to provide an improved form of resilient support for filaments, which support is easily assembled and enables the filament to be located and tensioned accurately.

Another object is toprovide an improved manner of supporting the usual filament tensioning hook so as to provide the proper tension to the filament.

A feature of this invention relates to a filament tension-hook support, by reason of which the proper tension may be applied to the filament, and the hook is maintained in a given plane during fiexure thereof.

Another feature relates to a filament tensioning hook assembly which is well-suited for use in tubes or lamps having a plurality of filament sections.

A further feature relates to the novel organization, arrangement and relative location of parts which go to make up an improved filament tensioning assembly for radio tubes, electric lamps and the like.

Other features'and advantages not specifically enumerated will be apparent after a consideration of the following detailed descriptions and the appended claims.

While the invention will be described herein as embodied in a known form of radio tube, it will be understood that this is done merely for purposes of explanation and not by way of limitation, and that the invention can be embodied many other form of radio tube or electric lamp as will be apparent to those familiar with these arts. Accordingly in the drawing,

Fig. 1 is an elevational view, partly in section, of a radio tube embodying the invention.

Fig. 2 is an enlarged detail view, in top plan, of the filament tensionlng assembly of Fig. 1.

Fig. 3 is an elevational view of Fig. 2.

Fig. 4 is a top plan view of a modification of Fig. 2.

Fig. 5 is an elevational view of Fig. 4.

Fig. 6 is a detail view of the filament hook shown in Figs. 4 and 5.

Fig. 7 is a top plan view of another modification of the invention.

Fig. 8 is an elevational view of Fig. 7.

Fig. 9 is a sectional view taken along the line 9 9 of Fig. 4.

Referring more particularly to Fig. 1, there is shown a typical radio tube comprising an enclosing envelope I, to which is sealed the press or header 2 carrying the various lead-in and support wires 3 to 9, and the electrode assembly, it being understood that in certain respects the showing of Fig. 1 is essentially diagrammatic. Merely for purposes of explanation the tube shown in Fig. 1 is of the triode type comprising a filamentary cathode II), a helically wound wire grid II, and a tubular metal plate or anode Ill. The grid I I is formed with a pair of parallel uprights or side-rods I3, I4 and the plate II is provided with a similar pair of uprights or side-rods I5, I 6, it being understood that the turns of the helical wire grid are fastened to the side-rods I3, I4 in any well-known manner, and likewise the side-rods I5, I6 are fastened to the plate I2. The filament has its free ends fastened, preferably by welding to the wires, 5, I while the bight of the filament is supported in the manner about to be described.

The upper ends of the various electrodes are supported and spaced apart by the usual mica insulator I l which is provided with perforations through which pass the, various side-rods I3, I4, I5 and'IB. The mica spacer I! may be fastened in place in any well-known manner, as for example by means of the metal straps I8, I8 welded to the plate I2. Preferably, although not necessarily, the mica is provided with an additional perforation through which passes the upper end of the filament support rod 6. Likewise the mica is provided with an elongated perforation 20 through which the filament hook 2| passes to engage the bight of the filament. The hook 2| and its shank 22 are made of spring wire such for example as steel, molybdenum or the like. For the purpose of locating the hook and for the purpose of facilitating giving the proper flexure to the hook shank 22, there is provided a substantially U-shaped metal frame member which is fastened, as by welding, to the support rod 6. Preferably the member 23 is fastened to the rod 6 so that the legs 24, 25 are in a plane at a small angle to the horizontal. When the various electrodes of the tube mount have been assembled and fastened to the wires 3 to 9, the mica I! is assembled over the side-rods and is fastened in place by the straps I8, IS. The member 23 is then welded to the rod 6, and the shank 22 is positioned as shown in Fig. 3, with its left-hand end disposed underneath the leg 24, and its median portion in engagement with the upper face of leg 25, it being understood that the hook 2I is engaged with the bight of the filament as shown. If desired the frame may be so welded that the point of intersection of 22 and 24 is in a substantially horizontal line with the filament hook and bight as illustrated for example in Figs. 5 and 8. The shank 22 may then be moved in any desired direction to center the filament with respect to the remaining electrodes. If the tension exerted by the shank 22 is not of the right magnitude, the shank 22 may easily be removed. from the member 23, and may be given the proper flexure as desired. When the member 22 has been given the desired flexure to impart the proper tension to the filament, and when the said member 22 has been adjusted to locate the filament properly, the member 22may be welded to the leg 24 as indicated by the numeral 26.

In certain types ofi adio tube mounts, either because of the delicate nature of the parts or because of the difficulty of inserting a Welding tool to effect welding of the shank 22 to the frame 23, it may be desirable to locate and anchor the hook and shank without welding. For this purpose, and as shown in Figs. 4 and 9, the frame member "23 is provided with locating notches to receive 'the shank 22. Thus as shown in Fig. 9 the under facefof the leg 24 is provided with a notch 21, and the upper face of the leg 25 is provided with a corresponding notch 28. Preferably the lefthand end of member 22 is hooked or offset as indicated by the numeral 29 so as to prevent relative movement with respect to the frame 23, While at the same time allowing the member 22 to be flexed tothe required amount.

The foregoing described method of resiliently supporting the filament may be applied to tubes having two or more filament sections. Thus as shown in Figs. 7 and 8, there are shown two filament sections 30, 3| and instead of employing a U-shaped frame for supporting the filament hook and shank, this frame may be substantially S- shaped as illustrated in Figs. '7 and 8. The frame 32 is Welded or otherwise fastened to the support rod 6, and a pair of members 33, 34 similar to the member 22 (Fig. 6) are employed, one for each of the filament sections. The members 33, 34 may be welded to the frame member 32 at the points of intersection therewith as described in connection with Fig. 1, or the frame member may be notched, as described in connection with Fig. 4, to retain the members 33 and 34 in adjusted position.

In the foregoing embodiments mention has been made of the fact that the filament hook and shank members may be readily removed from the associated frame members to impart the proper fiexure thereto. .However this method of imparting the proper fiexure, and also the proper tension to the filament, is not the only one that may be followed. For example the filament hook and shank may be assembled as shown in Figs. 2 and 3 and the leg 24 may be tilted or bent with respect to the rod 6 to correspondingly raise or lower the hook 2| until the proper tension is imparted to the filament. By a combined preadjusted flexure of the shank 22, and the later adjustment of the frame 23 it is possible to give a very highly accurate degree of tension to the filament.

Various changes and modifications may be made in the disclosure without departing from and a supportfor the spring member said support including a frame-like member having a pair of spaced arms and mounted so that part of the length of the shank engages the upper face of one arm of the frame-like member and another part of the length engages the lower face of the other arm of the frame-like member, the points of engagement between said shank and said arms being at different parts of said shank.

2. A resilient support for a filament comprising a spring member having a hook portion to engage a vertical filament bight and a shank portion, and means engaging the under face of the shank intermediate its ends and engaging the upper face of the shank adjacent one end for the purpose of controlling the degree of fiexure of said shank, the last-mentioned means including a pair of spaced parallel arms the plane of the arms extending substantially perpendicular to the filament.

3. A resilient supportfor a filament comprising a spring member having a hook portion to engage a filament bight and a shank portion, a filament support post, a frame member carried by said post and having a pair of spaced arms, said shank being mounted at an angle to both said arms and engaging the under face of one arm and the upper face of the other arm. a

4. A resilient support for a filament comprising a spring member-having a hook portion to engage a filament bight and a shank portion, a filament support'post, a pair of substantially parallel bars one of said bars being fastened to said support post and. the other bar being adjustable with respect to said support post, said shank being mounted in intersecting relation to both said bars and engaging the upper face of the said one of said bars and the under face of the other of said bars. 7 V

5. A resilient support fora filament comprising a spring member having a hook portion to engage the bight of a filament andashank portion, a support post, and a frame-like member having a pair of substantially parallel arm'ssaid member being fastened to said post so that one of said arms is adjustable with respect to said post,

said shank being mounted substantially perpendicular to both arms with part of its length engaging the under face of one arm and another part of its length engaging the upper face of the other arm.

6. A resilient support for a filament comprising a spring member having a hook portion to engage the bight of a filament and a shank portion, a support post, and a member having a substantially U-shaped portion with one'of the legs of the U fastened to said support post, said shank being disposed in intersecting relation to both legs of the U and having part of its length engaging the upper faceof one of the legs of the U and another part of its length engaging the under face of the other leg of the U.

7. A resilient support according to claim 6 in which the part of the shank which engages the under face of the U is rigidly fastened thereto.

8. A resilient support according to claim 6 in which the part of the shank which engages the under face of the U is hooked.

9. Means to support and adjust the tension of a filament including a support post and a substantially U-shaped metal member fastened to said post but being adjustable with relation thereto.

10. In combination av filament having a bight,

a filament support post, an adjustable arm mounted substantially perpendicular to said post but in spaced relation thereto, a spring member having one end engaging the under face of said arm and the other end engaging the filament bight, and a member fixedly mounted with respect to said post and engaging the spring member intermediate its ends to provide a fulcrum therefor.

11. The combination according to claim 10 in which the second-mentioned member is notched at the point where it engages said spring member and said spring member lies in the notch.

12. The combination according to claim 10 in which the said one end of the spring member is hooked where it engages said arm and said arm is notched at the point of engagement, and said second-mentioned member is also provided with a notch in alignment with the notch in said arm said spring member lying in both said notches.

13. In combination a pair of filament sections each having a bight, a member having a pair of substantially U-shaped members, a support post to which said member is fastened, a pair of spring members each having a shank and a hook to engage a corresponding filament bight, each shank being disposed between the legs of a U- shaped member so that one leg of the U acts as a flexing fulcrum for the spring and the other legs acts an anchor for the spring.

14. The combination according to claim 13 in which the U-shaped members are joined together to form a substantially S-shaped member.

HENRY J. MoCARTHY. 

